The present invention relates generally to speed control systems for electric motors and specifically to a speed control system based upon motor load for the electric motor in a powered textile floor covering brush.
Brush vacuum cleaners are used to clean textile floor coverings, where, in addition to a dirt aspirating air flow, there is also a roller-like brush provided to detach the dirt particles adhering to the floor covering. This roller-like brush is driven by an electric motor through an intermediary belt and can be so adjusted in height with respect to the floor surface so that the bristles of the roller-like brush penetrate the pile of the carpet in order to dislodge dirt in the carpet-pile fibers. In this manner both the dirt adhering in the carpet pile is loosened and the fibers bent by walking on them are righted. However there is a difficulty in that the pile-height of textile floor coverings can differ substantially. For instance there are coverings with a smooth, felted surface, and also high-pile or long-pile carpets of which the fiber bundles are mostly twisted like yarn and may be up to 30 mm long.
In order the clean various textile floor coverings using a roller brush which is mounted into a suction nozzle of a vacuum cleaner, different angular speeds of the roller brush are required to achieve the highest possible cleaning effect. For instance, smooth felted surfaces as well as cut-pile carpets with a pile height of 5-6 mm can be cleaned at brush speeds of about 6,000 rpm, whereas substantially lesser brush speeds of about 3,000 rpm may be appropriate to clean high or long pile carpets.
In prior art brush vacuum cleaners or adapter suction means, two different values can be set for the rotational speed of the roller brush. The setting of the appropriate rotational speed is generally performed manually, and frequently the wrong brush rotational speed will be set either due to the ignorance of the operator or forgetfulness. If the rotational speed set is excessive, the motor may be overloaded and excess stress is placed on high or long pile carpets, and too low a rotational speed may result in inadequate cleaning.